The use of fastening devices for the closure of containers, including plastic bag bodies, is generally known. Furthermore, the manufacture of fastening devices made of plastic materials is generally known to those skilled in the art relating to closure devices, as demonstrated by the numerous patents in this area.
A particularly well-known use for fastening devices is in connection with flexible containers, such as bag bodies. The closure device and the associated container may be formed from thermoplastic materials, and the closure device and sidewalls of the container can be integrally formed by extrusion as a single piece. Alternatively, the closure device and sidewalls may be formed as separate pieces and then connected by heat sealing or any other suitable connecting process. The closure devices when incorporated as fasteners on bag bodies have been particularly useful in providing a closure means for retaining the contents within the bag body.
Conventional closure devices utilize mating male and female closure elements which are occluded. When conventional closure devices are employed, it often is difficult to determine when the male and female closure elements are occluded. This problem is particularly acute when the closure devices are relatively narrow. Accordingly, when conventional closure devices are employed, there exists a reasonable likelihood that the closure device is at least partially open.
The occlusion problem arises from the inability of a user to perceive when the male and female closure are occluded to form a seal between the contents of the bag and the environment external to the bag. A number of solutions to this problem have been attempted. For example, U.S. Pat. Nos. 4,186,786, 4,285,105, and 4,829,641, as well as in Japanese patent application No. 51-27719, disclose fasteners that provide a visual indication that the male and female closure elements are properly occluded. Specifically, a color change means for verifying the occlusion of the male and female members of the closure is provided wherein male and female members having different-colors are employed, and, upon occlusion, provide yet a different color. For example, the female member of the closure may be opaque yellow and the male member of the closure may be translucent blue. Upon occlusion of the male member and female member a composite color with a green hue results. This use of a color change greatly improves the ability of the user of the interlocking closure device to determine when the male and female members are occluded.
The change in color that is viewed when dissimilarly colored male and female members are occluded is demonstrated in a commercially available product sold under the trademark GLAD-LOCK (Glad-Lock is the registered trademark of The Glad Products Company of Oakland, California, formerly First Brands Properties, Inc., Danbury, Conn.). This color change effect may be enhanced by the incorporation of a color change enhancement member in the closure device, as disclosed in U.S. Pat. No. 4,829,641.
Color-changing closure devices are not a universal solution to the aforementioned problem of assuring full closure, however. For example, the color-change effect is imperceptible in the dark, thus mooting the color-change advantage of the closure devices when they are used under such conditions. In addition, sight-impaired or color-blind people may not be able to perceive the color-change effect. Accordingly, it would be desirable to provide a closure device that affords other indications of occlusion.
The prior art has attempted to furnish a fastener that provides a tactile or audible indication of occlusion. For example, U.S. Pat. Nos. 4,736,496, 5,138,750, 5,140,727, 5,403,094, and 5,405,478, as well as EP 510,797, disclose closure devices that allegedly provide a tactually or audibly perceptive indication of proper interlocking of the closure elements. It is said that, upon occlusion of the disclosed closure devices, a user is able to feel or hear that full closure is accomplished. For example, U.S. Pat. No. 4,736,946 discloses the use of additional ribs on either side of the closure elements. These ribs are said to give an improved "feel" to the closure, thus aiding a user in aligning the closure elements.
Such devices are difficult to handle by individuals who have limited manual dexterity. Thus, in order to assist these individuals and for ease of use by individuals with normal dexterity, the prior art has attempted to furnish a fastener that provides a reclosable fastener and a slider for opening and closing the fastener. For example, several U.S. Patents disclose fasteners with sliders. However many of these fasteners use either: (1) a separator finger which extends between the closure elements, such as U.S. Pat. Nos. 3,054,434, 3,115,689, 3,122,807, 3,230,593, 3,426,396, 3,713,923, 4,199,845, 4,262,395, 5,007,142, and 5,010,627 (FIGS. 9 and 10); or (2) the separator finger runs along a track above the closure elements, such as, U.S. Pat. Nos. 5,007,143, 5,010,627 (FIGS. 3-8), 5,020,194, 5,067,208, 5,070,583, 5,088,971, 5,131,121, 5,161,286, 5,283,932, 5,301,395, 5,426,830, 5,442,837 and 5,448,808.
With respect to fasteners which use a separator finger which extends between the closure elements, these fasteners do not provide a leak proof seal because the separator finger extends between the closure elements. With respect to the fasteners which run along a track, the fastener typically include slits, notches or another means to accommodate the separator finger in the end position. These means are used to achieve occlusion of the closure elements at the end position and thus attempt to achieve a leak proof seal. For example, U.S. Pat. Nos. 5,020,194, 5,067,208, 5,088,971, 5,131,121, 5,161,286, 5,301,394, 5,301,395, and 5,442,837 use a slit, notch or other means to accommodate the separator finger in the end position. These means in the fasteners create additional steps in the manufacturing process and thus may increase the cost of these fasteners.
A reclosable fastener with a slider and without a separator finger nor the use of a track is described in U.S. Pat. Nos. 3,074,137 and 5,442,838. However, the fastener in the '137 patent would be too expensive to manufacture and may not seal when the slider is in the end position. With respect to the fastener in the '838 patent, the slider does not manipulate the interlocking elements directly. Rather, the slider engages the structure located below the interlocking elements to control the opening and closing of the interlocking elements. Difficulties and additional variables can arise when the slider does not act directly upon the interlocking elements. In addition, the fastener in the '838 patent may not operate properly if the tolerances are incorrect for the slider and/or the fastener. The structure below the interlocking elements and/or the slider may be difficult to extrude or manufacture. If the tolerances are incorrect, the slider may not move smoothly or fail to open or close the fastener elements. Thus, it would be difficult to achieve a properly functioning fastener.
Thus, the prior art has failed to afford a closure device with a slider and a separator finger which establishes a leak proof seal without the use of slits, notches or other means. It is a general object of the present invention to provide such a closure device. It is a further general object of the present invention to provide a container that is closeable and sealable by means of such a closure device.